Ultra high frequency device



NOV'v 30, 1948 w. l... BARRW Erm. 454,761

ULTRA HIGH FREQUENCY DEVICE l mvENToRs E wlLMER I .BARRow j.wALTERwMlEHER NOV. 30, 1948. w, BARROW l-AL 2,454,761

4 V ULTRA HIGH FREQUENCY DEVICE l Filed Nov. 2Q, 1942 y s sheets-sheet 27 lll/IIIA I .WILMER L. BARROW WALTER W. M IEHER ATTORNEY NOY. 30, 1948.w"| BARROW ETAL 2,454,761

ULTRA HIGH FREQUENCY DEVICE v Filed Nov.,2o, 1942 A s sheetssheet sINVENToRs WILMER L. BARROW WALTER W. MIEHER Patented Nov. 30, 1948:Unirse .smi-ies rare-Nr ortica UL'rRA nlcnclcrrcv nevica.

I:Wilmer L. Barrow, 1Concord, Mass., and Walter Micher, Mineola, :N.fY., .assigners to The :Sperryr-LGorporation, a corporation of sDelawareApplication November 2o, 1942,.s`eria1N0. 456,530

This invention relates, generallyg'to'ultrahigh frequencyftransmission,and, Ymore particularly, to a type of gas-*discharge resonant tubeuseful in stopping the flow, through a waveguide or other conductor, ofultra "high frequency energy above a predetermined. adjustable maximum..amplitude and' in allowingenergy below that amplif tude to flow,substantially unattenuated, and also I be placed. This Afeaturerestricts the physical to apparatus for conveniently and removablymounting such'tubes and other apparatus in a wave guide circuit. i 1

Such devices havebeenfound useful in ,ultra high frequency ipulseradiating and .receiving systems. weight considerations .demand that a`single `lievice serve `both as a transmitting .and receiving antenna.The device Aofithe lpresent.invention makes it possible for high energytransmitter pulses to be introduced into a waveguide also utilized-bythe receiver, in. such a manner that the yreceiver is "not paralyzedorpermanently damaged Vby the-high energy ofthe transmitted pulses.

In common penance, thisgasdischarge device has come to he' known as arT-Rhox, an abbreviation for the 'term transmissionreception box, andwillibe referred to"inthe`.following specicationas such. y

The T-R'boxes of theiprior art-have been,pro vided with a gas-enclosing`metallic! resonant` cas]- ing or enclosure having glass or otherceramicwalls or'windowsthrough whichthe Aradio frequency energy enters orleaves vuthebox. The enclosure also contains discharge electrodes whichare adapted `to provide 'a ygas discharge within the -enclosure inresponse to highiintensity received energy, to-destroy -theresonantcondition of the lenclosure and thereby-tohlock `the passage ofsuch-energythrough the device. `In such devices itiis a practicalnecessity ,toiform the glass or ceramic windowsvvithinthe casing wallsbefore `fully enclosing the casing, `as by soldering,V hrazing` or`welding the metalto-metal joints. t

In previous devices of lthis-,type Ythe `forming or the metaljointswasextremely difficult, since particular painshadtol-lloc' taken to`preventy damage to the 'glass'or'ceramic'windows. This'is especiallythe'casefsince lprior -art TeRboxes have been designed forvoperationywithelectrical resonance ofthe'fundamentalor dominant resonant mode,lfor `which 4the operating'ffrequency is the lowest permissible for4resonance" to f occur. In suchT-Rboxes,:there-iseonly one 'point ofvoltage maximum, Aat whichlthe windows should Y In many suchrsystems,space .and

shapeanddimensions of the casing and the location ;.o`ffthewindows`, sothatthe above-discussed disadvantages -in the electrical and fmechanical design andmanufacture are present.

" Alsoftloe gas discharge between the `electrodes tends to evaporatesomeof the material of these electrodes, so that afilm vof this metal, ,orother material `formed by interaction of the metal vapor andthe gas, isdeposited on'the glass or other ceramic walls.` This film continues tobuild up with the continued use oi the T-R box,;and harmfully affectstheentrance or egress of radio frequency energy fromthe box while alsocausing serious power losses. Eventually this film renders the T-R boxunusable and makes replacement necessary.

In prior art systems, it has been the practice to ,solder-orotherwisepermanently seal the T-R box directly into its connecting wave guides orother high frequency energy conductors, in order toprevent loss ofenergy yatt-he joints. However, the finite life of these devices due tothe causes just described makes the permanent installation of the devicein-the conducting system impracticable.

According to thepresent invention, theseprior art'defects aresubstantially overcome. An improvedtype of T-R box isprovided in whichresonanceoccurs .ata higher mode of resonance than the fundamentalmodes, so that more points of voltage maximum'areobtained, wherebytheglass `or ceramic windowsmay .be spaced from the metaljoints whereby therequired soldering, brazing or Welding. of thesemetal joints will havelittle .effect upon the windows, and a .greater flexibilitydnelectricaland mechanical designl and manufacture may be obtained.` Furthermore,`the discharge electrodes are so located as toreduce and delay formationof the harmful film on the windows, lthus `providing longer life andlower losses. In addition, an improved form of holder for'suchdevicesisprovided, adapted toremovablysupport such`T`RboXes orother similar devices, with a minimum ofenergy `loss and impedancemismatch at' the improved j ointsforrning a part of theholder.

It is therefore a principal object ofthe present inventlonto provideimproved form of T-R box having a rugged typek of construction suchthatdamage is unlikelyeven under roughmilitary, navalor other serviceconditions.

It is another object of the present invention to provide ran .improved.construction of LTR boxes or other similar devices in which neces- 3sary glass-metal seals are relatively removed from soldered, brazed orwelded metal joints, whereby the construction of the device is improvedand its manufacture is facilitated.

It is still another object of the present invention to provide animproved form of T-R box adapted to be plugged into a wave guide orother high frequency energy conductor system, and to be easily removabletherefrom.

It is yet another object of the present invention to provide an improvedT-R box operating at a higher mode of resonance whereby advantages inelectrical and mechanical design and manufacture are obtained. Y

It is a further object of the present invention to provide a socket orholder means in' a wave guide or high frequency energy conductor systemfor removably supporting a T-R box or other ultra high frequency device,without permitting energy to leak through the joints therein into spaceor to bypass the device, and to provide minimum impedance discontinuityat the joints.

A still further object of the present invention is to provide improvedimpedance matching means at joints presented to the flow of highfrequency energy, whereby impedance discontinuities to the energyleakage are avoided.

Other objects and advantages will become apparent from the specificationtaken in connection with the accompanying drawings, wherein theinvention is embodied in concrete form.

In the drawings,

Fig. 1 is a schematic block diagram, showing a system in which a T-R boxaccording to the present system may be used.

Fig. 2 is a longitudinal cross-sectional view of a preferred form of theT-R box of the present invention.

Fig. 3 is a perspective cross-sectional view of a T-R box or other waveguide accessory holder according to the present invention.

Fig. 4 is a fragmentary cross-section View taken along the lines 4-4 ofFig. 2.

Fig. 5 is an explanatory graph.

Fig. 6 is a fragmentary longitudinal crosssection view of an alternateform of a portion of Fig. 2.

Fig. 7 is a partial cross-section view of another form of the invention.

Fig. 8 is a cross-sectional view taken along the lines 8-8 of Fig. 7with the structure 'l' rotated slightly.

Fig. 9 is a cross-sectional view of an alternate form of the device ofFig. 7.

Fig. 10 is a fragmentary cross-sectional view taken along the lineIIl-ID of Fig. 9.

Fig. 11 is a fragmentary cross-sectional view of another modification ofthe device of Fig. 7.

Fig. 12 is a fragmentary cross-sectional view taken along the line I2-I2 of Fig. 11.

Fig. 13 is a fragmentary cross-sectional view of a further modificationof the invention.

Fig. 14 is a fragmentary cross-sectional view taken along the line I4I4of Fig. 13.

Fig. 15 is 'a partial longitudinal cross-sectional View of still anotherform of the invention.

Fig. 16 is a plan cross-sectional view of yet another form of theinvention.

Fig. 17 is a longitudinal sectional View of another form of highfrequency device cooperating with the holder of the present invention.

Similar characters of reference are used in all of the above figures toindicate corresponding parts.

Referring now to Fig. 1, there is shown a block diagram of anillustrative system using a T-R box, shown as a pulse-type objectlocation system. High energy pulses from a pulsed transmitter 2 are fedby means of a wave guide 3 or other high frequency energy conductor intothe wave guide 4, and thereby to a reflector or other antennaarrangement 4. Wave guide 4 forms a T-joint with guide 3, and is alsoconnected to the T-R box I, whose other end is connected to a Wave guide5 leading to a receiver 6. T-R box I is so designed that when a pulse isemitted by transmitter 2, the T-R box is made non-conducting, as will bedescribed, so that substantially all the energy of the transmitted pulseis rejected by the T-R box I and substantially none is introduced intothe receiver 6. This transmitted pulse is emitted by antenna 4', and, inthe illustrative system used, may be reflected by any object within theradiation pattern of the antenna 4. Depending upon the size of theobject and the distance between the system and the object, thetransmitted pulse is reflected and returns to the antenna 4' somewhatattenuated and after a time delay corresponding to the distance betweenantenna 4 and the reflecting object. The energy of this received pulseis considerably smaller than the transmitted energy. T-R box I isaccordingly made conducting to this lesser energy, so that this receivedpulse is transmitted directly through the T-R box I substantiallyunattenuated, to be received and utilized by the pulse receiver 6. Pulsetransmitter 2 is designed so that its admittance to the received pulseis low, so that little of the reflected pulse energy is absorbed bytransmitter `2. T-R box I thus serves to protect' the receiver from highenergy intensities. 'It will be clear that many uses exist for such T-Rboxes other than the illustration just given.

As seen in Fig. 2, the T-R box I consists, in a preferred form, mainlyof v`a resonant chamber or resonator'l. The two wave guides 4 and 5xedly terminate in an external holder or socket 8, and which removablysupports resonator l. The resonant `chamber 'I itself is 'preferablymade cylindricaLlits cylindrical wall l -being of some such alloy as thecommercially well-known alloy Kovar, Vand has" its external and internalSurfaces plated with material of high electrical conductivity, such assilver Ior copper. In the form of the invention shown in Fig. 2, theresonator l is closed at one end with a rigid wall 9 and at its oppositeend by a flexible diaphragm I0.

Reentrant from a 4central aperture in end wall 9 is .a tube` I5 whichextends into the resonator 1 nearly toend wall I D. The internal end oftube I5 is conical, and has a small hole I7 centrally positioned at theapex thereof. Coaxially positioned within tube I5 is a conducting rod2D, which terminates in a conical point 2l just inside of hole I l. RodZIJ is positioned with respect to and electrically insulated from tubeI5 by a metal-to-glass seal 22. Centrally fastened in a central aperturein the diaphragm ID is a conical bluntly-pointed conduc'tor 2.3, whichreaches to within a short distance of the hole Il. Rod 23 is extendedthrough the diaphragm I 0 and .threaded outside of the diaphragm IIJ, asat 24, to be axially adjustably moved by rotation of a nut 25 which isfixed axially relative to the outer cylindrical wall 'l' of resonator 'lby means of end bracket 26 fixed to Wall l', whereby the operating pointof .the T-R box may be adjusted, vas will be seen. Bracket 26 alsoserves as a mounting device for the T-R box. A pairuof openings II andII2 .are made in the to a very low level, as shown by the portion 32 ofthe curve 3l' of Fig. 5. In this way, the high intensity pulse 30 issubstantially blocked by the T-R. box.

When the main pulse is over, this high-current discharge between l1 and23 ceases, the T-R box becomes tuned again, so as to be capable ofpassing energy from the low energy reflected pulse to the receiver 6.

The gap between electrodes l5 and 23 is preferably placed as far aspossible from windows Il, l2, so as to prevent any metal sputtered fromelectrodes i5 and 23 during the interval when the discharges occur, fromcondensing on windows Il, l2, thus preventing aging of the device byincreasing the attenuation of these windows.

The breakdown point of chamber 'l and hence the point of demarcationbetween the pulses transmitted and blocked thereby may be adjusted bymeans of knob 25.

The T-R box just described is adapted to be removably held within aholder fastened permanently to the remainder of the system, in order topermit ready replacement upon deterioration or damage. In the past,great difculty has been experienced in providing removable devices forconnection in an ultra high frequency system such as the present system,since the necessary joints required to provide removability introduceundesirable and harmful impedance discontinuities and also permitleakage of energy outside the system and around the removable device,which may be a T-R box as in the present illustration, or any other typeof high frequency device similarly' insertable in the system.

According to the present invention, these former difliculties areovercome by the provision of special features in such a holder for aremovable device, which minimize the effects noted above. A mounting isprovided in which the coupling between T-R box and wave guides takesplace without surface-to-surface contacts playing any part in theelectrical operation, thus removing entirely any variations,irregularities or losses associated with such contacts. In the presentillustration, the T-R box described above, or any other similar device,is adapted to be removably held within a holder or socket arrangement 8,as by means of suitable fastening members 26 holding bracket 26 firmlybut removably against the thick wall 4t of holder 8. Wall 40 is made ofhighly conductive material with its in'- ner conducting surface 4I ofslightly greater diameter than the outside diameter of resonator l, andis substantially of the same length as that of resonator l.

Wave guides 4 and 5 are rigidly positioned in wall and extendtherethrough to form openings directly opposite windows H and I2. Aboveand below wave guides 4 and 5, at a distanc-e of substantiallyone-duarter-wavelength of the operating frequency, are placed annulargrooves 4l and 42 extending radially for a distance of aquarter-wavelength of the operating frequency. These grooves 4i and 42and the space between resonator 'l and cylindrical wall 4l] form afilter and impedance matching system, to prevent high frequency energyfrom leaking from the interior of wave guides 4 and 5 out of the top orthe bottom of the socket or holder 8, and to minimize the impedancediscontinuities at the joint between the holder 8 and the T-R box.

To explain the operation of this portion of the device, grooves 4I and42 may be considered to constitute quarter-wave sections of atwo-conductor transmission line, short-circuited at their remote ends,such as at 43, by the conductive material of wall 40. As is Well known,such a short-circuit quarter-wave transmission line presents a very highimpedance at its open end, as at 44. In the apparatus of Fig. 2, thishigh impedance is effectively in series with the unknown impedance whichis characteristic of the space between holder 8 and resonator 7.l Theseries connection of such a high impedance with an unknown impedancenecessarily yields a resultant very high impedance. The quarter-wavetransmission line formed by the concentrically disposed inner wall 4i ofholder 8 and the outer wall 'l' of the T-R box transforms this resultanthigh impedance into a very low impedance at point 45. Accordingly, thegap at 45 presents an extremely low impedance to the iiow of energythrough wave guide 4 into the T-R box. By virtue of this condition, thephysically necessary discontinuity at this point has little effect uponthe system, and little or no energy leaks outwardly from the joint, atleast in the longitudinal or axial direction of the T-R box. Even thoughthe dimensions herein referred to are not held to exactly, a substantialblocking of the egress of energy will result.

It will be clear that the explanation offered for slot 4I and wave guide4 applies equally well to the remaining slots and wave guides.

As seen more clearly in Fig. 3, means `are provided to prevent whateverhigh frequency energy is propagated longitudinally from the joint from rtravelling around annular grooves 4l, 42, which are similar to waveguides extending around and bypassing the resonator l, and thereby outfrom guide 5 Substantially 20 displaced from the wave guides 4 and 5,and a quarter-wave from the edges of the guides, is placed a verticalslot 46 which has a depth of a quarter-wavelength. VThe crossover pointsbetween annular grooves 4| and 42 and vertical slot 46 are blocked tohigh frequency energy by means of conducting pins 4l and 48, or by otherconducting means, so that there can be no communication of energybetween the annular grooves 4l, 42 and the slots 46. Also, pins 47, 48prevent the ow of energy through grooves 4 I, 42. Slot 46 then acts in amanner similar to that of the grooves 4l and 42, to prevent energy frombypassing the resonator l. If the circumferential distance betweenadjacent edges of wave guides 4,

5 is substantially greater than a half-wavelength,

a pair of slots, placed a quarter-wavelength respectively from waveguides 4 and 5, may be used in place of the single slot 46.

In order to more easily construct'l the holder and to conserve material,it is not necessary that the filter grooves 4| and 42 be formed in asolid block of metal 4U as shown in Figs, 2 and 3. They may also be madeby simply fastening the lter structure to a thin wall tube 53 formingthe outside of holder 8, as in Fig. 7. In Fig. '7, annular quarter-wavedeep'sections 54 and 55 are provided on opposite sides of the waveguides 4 and 5, and in; side of Wall 53, the open ends 58, 51 of thesections 54, 55 being located a quarter-wave distance from the upper andlower conducting surfaces 60, 6| of the'guides 4 and 5. These sections54, 55 operate in exactly the same manner as explained in Fig. 2 toprevent axial leakage and to provide minimum impedance at the joint.

As shown in Fig. 8, if the Windows Il and l2 are rotated relative to theopenings of the wave guides 4 and 5, the coupling between guides 4 and 5may i rae-bepm be altered, thus effectively varying thef'Qand thecoupling o'f the system. As shown, `an equal change in the coupling ofthe T-R box to the'two wave guidesis provided by any rotationaladjustment of the T-R box. Obviously, it fcouldbe arranged to change thecoupling to one guide only if desired, as by providing a variable anglebetween the axes of the two guides terminating in the holder, and byother means readily apparent to one skilled in the art.

As seen in Fig. 8, :filter means, similar to that shown in Fig. 7 tosuppress leakage of energy out of the top and bottom of holder 8, may bealso placed vertically on each side of the .resonator 'I in order toprevent energy from bypassing the resonator. For this purpose, in theannular space between shell 53 and the casing I of T-R box I there areplaced two members 66, 66' formed as longitudinal sections of a cylinderand concentric with respect to shell 53. each of these members, such asl[i4 and 64', are spaced from the edges 65, 65' of the wave guides l and5 by substantially a quarter-wavelength. Connecting members 6E, 55 withshell 53 are members 63, 63 which are chosen to have such a width thatthe members, 66 `provide a quarterwavelength short-circuited linesections in a mann ner similar to that shown in Fig. -3. It will-beclear that these devices will perform in the same manner as those ofFig, 3 to prevent bypassing of the rll-R box -I by the 4high .frequencyenergy flowing between wave guides 4 -and 5. Members 66, B6' may beformed integrally with ilanges 54, 55 of Fig. 7, whereby members 63, 63prevent bypassing cf T-R box 'l through the sections 54, 55.

Figs. 9, l1 and 13 show several modications of the arrangement of Fig.7, all operating upon the same general principle. Thus, in Fig. 59, thequarter-wave short-circuited line section -12 is formed outside of shell53 and communicates with" the interior thereofbyannular slot 10.Asbefore, section 'I2 is separated from wave guide 4 by substantially aquarter-wavelength. InFig. 1,1, section l2 is shown folded downwardinstead of upward, but otherwise similar to that of Fig. 9. Fig. i3 issimilar to Fig. 7, merely reversing the direction in which theshort-circuited quarter-wave section 54 extends. It will be clear thateach `of these modifications will operate in the same manner as Fig. '7and Fig. 2 to prevent axial leakage of high frequency energy andtomaintain a minimum impedance at the joint between thehol-der and T-Rbox I. Obstructions equivalent in function to pins 48 of Fig. 3 may alsobe used in these figures.

Figs. l0, 12 andll show modifications of Fig. '8, corresponding to theirrespective i'lgures,"9, 1l and 13. In each of these cases againtheintermedi'ate external leakage impedance is connected in series witha short-circuited quarter-wave 'line section and the resultant seriesimpedance is transformed at the opening of the 'wave guide 'to a verylow impedance to provide minimum impedance at 4the joint and to preventenergy leakage. These lfigures are otherwise self-explanatory.

If desired, the windows II, I2 of Figsbl and 7 need not be oppositelylocated, but maybe placed at any suitable orientation or locationrelative to each other, as `pointed out above. In Fig. 15., wave guide Ais `shown fastened into fa rotatable lter structure I05 opposite windowfII., while wave guide 5 is shown positioned in 'a iilter structure IBSopposite a window laterally, and if desireclfalso angularly, displacedfrom window I I'. Filter structures |05 and :IUE are `shown .similar tothe `The lea-ding edges of J 310 Ettf-'pe described in T9, `but may-beof any suitable Filter fstructures -III5 and `IIlI may be madeindividually-rotatable withrespect *toichamber 'I lsothat waveguides!!and A5i' maybedisposed at any desired "angle, The construction of this5modilisation-ha`s the advantage of `separating rlater'allythe filterstructures of a'the two wave guides and Windows, and thus decreasing thelikelihood 4of transfer-of 'energy 1from 'one guide tothe otherthroughthe holder without passage through the further means for`preventing energy `from bypassing fthe resonator Jl is shown 'in Fig.-16, fwhich describes the application of a type of 4iilter structurefirst 'shown in a coaxial-line type yof ultra high frequency filter "incopending applicavtion Serial iNo. 417,229, entitled A high fre- 'duency`tube structure, led October 31, 1941, in the 'name of William W.Hansen. `External I'holier Wall 53, into which wave guides 4 and 5 areinserted opposite windows II, I2 in T-R vbox l, expands in thickness atalternate quarter-wave intervals around the circumference to form ap--proximately `quarter-wave long conducting members lI'I'U with `slightlygreater inner diameter ithan T-'R box 'I with similar unexpandedmemlbers "III-2. AIn designing the lter, the lengths of sections III)and II2 are selected by experi- .'ment .if inecessary, yto provide animpedance inyversion.'irom section `'to section by means of thevusual'quarter-wave 4transm'ission-line action such vthat .a 'very :loweffective impedance is caused to appear between -the wave guide 4 or 5and the oppositelydisposed T-Rrbox 1 or other device.

In the -illustration'shown'in Fig. 16, the impedance appearing, forexample, between guide 4 and T-R box 'I will be transformed by 'the`first adjoining quarter-wave' section vto 'a different impedance. Thefollowing pairs Vof quarter-wave sections, being alternately of low andhigh characteristic impedance, will transform this higher impedance to'a very low effective impedance appearing between -guide'5 and T-Rbox l.Thus, fthe wave energy -is forced to travel between the rguides and theinterior 'resonant 'space of the device without an appreciable amountcircumventing-the device.

`In the modification :shown in Fig. 16, an odd Inumber of quarter-wavesections are provided. Other numbersand arrangements of sections, in-4cluding even `sections of lengths different from a quarter-wave, may bedevised -by well known transmission-line theory by those skilled intheIt -is seen -that without the filter devices herein shown, includingthat 4of Fig. 16, the high frequency -energy will be propagated in theannular channel between wall -53 and resonator .'I :so as .to bypass the'If-R box at least in part. Any desired combination of the `iilter-means herein shown `may 1be utilized with T-R box holders, to preventboth axial `and `peripheral leakage yof energy. The socket devices hereshown are also applicable -to other types of tubes or `to otherultrahigh frequency devices, such as mixers, 'deteotora and the like,without Ibeing necessarily limited to use with T-R boxes.

For -example,l?ig. 157 lillustrates the -use of "a .holder similar Vtolthat of Fig. 7 with Van ultra :high-frequency velocity modulationelectron discharge device, such as `of the Klystron type `described inVarian Patent No. 2,242,275, issued May 20,1941. In `this gure, the -twowave guides d and 5 cooperate with respective -resonators +20 `and:.I2'I which are respectively the input and out put circuits of theKlystron device, here shown as being an amplifier as disclosed in theabovementioned patent, and having a cathode |22.

It will beclear that many other types of high frequency device could besubstituted for the T-R box or the Klystron device described in thepresent specification. Also, the holders of the remaining figures, suchas Figs. 2, 9, 11, 13, or 16 could be utilized in the same fashion asshown in Fig. 7. It is also evident that the T-R box herein disclosedmay be rigidly fastened tothe Wave guides, or may be used in any othermanner not described in the present disclosure. In particular, it isevident that the Wave-guide filter means of Fig. 16 may be used in manytypes of Wave guide applications.

Wherever distance is given in terms of wavelength in the above, it is tobe understood that the actual dimension is such as to give the sameelectrical effect as the given dimension would in vacuum, since allwavelengths given are those occurring in vacuum. v

As discussed above, the term higher mode of resonance (or equivalentexpressions) when used in the appended claims, signifies that theresonant frequency of the cavity resonator is higher than the lowest(fundamental mode) resonant frequency thereof.

As many changes could be made in the above construction and manyapparently widely different embodiments of this invention could be madeWithout departing from the scope thereof, it is intended that all mattercontained in the above description or shown in the accompanying drawingsshall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

l. A gas discharge device for ultra high frequencies comprising a cavityresonator having a gas-filled casing of a length for resonance at ahigher mode, said casing having a rigid end wall, a flexible end wall,and a'cylindrical side wall having a pair of apertures locatedsubstantially a quarter-wavelength from said rigid end Wall andrespectively providing an entrance and an egress in said resonator forhigh frequency energy; a reentrant tube coaxial with said casing andextending from said rigid end wall toward said flexible wall, 'said tubehaving an aperture in the end thereof adjacent said iiexible wall; afirst electrode fixed to said flexible wall; means operably connected tosaid first electrode for adjusting said rst electrode toward and awayfrom the end of said tube; la second electrode disposed Within said tubeand insulated therefrom; and means for maintaining a cold dischargebetween said second electrode and the apertured end of said tube,whereby a high intensity energy pulse entering one of said apertureswill break down said gas to detune said cavity and prevent passage ofsaid energy to the other of said apertures, while a low intensity energypulse will pass through said cavity substantially unattenuated, thebreak-down level of said cavity being adjustable under the control ofsaid adjusting means.

2. A gas discharge device for ultra high-frequencies, -comprising agas-filled cavity resonator resonant at the operating frequency of saiddevice, means operably connected to said resonator for coupling ultrahigh frequency energy to said -cavity at a voltage anti-nodal positionthereof, means operably connected to said resonator for abstractingenergy from said cavity also at a voltage anti-node, and means connectedto said resonator for maintaining a cold discharge therein at a voltageanti-node thereof spaced from said coupling and abstracting means.

3. A gas discharge device for ultra high frequencies, comprising agas-filled casing providing a cavity having dimensions for providing ahigher mode of resonance at the operating frequency of said device,means including a window in said casing for coupling lhigh frequencyenergy thereto at a voltage anti-nodal position of the field within saidcavity, and means within said casing responsive to high frequency energyof sufliciently high amplitude for causing a gas discharge in saidcavity and thereby detuning said resonant cavity, said last-named meansbeing spaced from said coupling means to prevent deterioration of saidwindow by the action of said discharge.

4. A gas discharge device for ultra high frequencies comprising agas-filled casing providing a cavity resonant at the operating frequencyof said device, means including a window in said casing for couplingthereto energy at said operating frequency, and means Within said casingresponsive to high frequency energy of suiciently high amplitude forproviding a gas discharge within said cavity to detune said cavity, saidlast means being spaced from said Window to prevent deterioration ofsaid window by the action of said gas discharge.

5. Apparatus for use with ultra high frequencies comprising meansproviding a cavity resonator for an operating frequency higher than thelowest resonant frequency thereof, means coupled to said cavityresonator at a voltage antinodal position thereof for supplying energythereto of said operating frequency, means coupled to said resonator forabstracting energy from said cavity resonator also at a voltageanti-node thereof, and means in said cavity resonator for preventingsaid abstraction of energy in response to high frequency energy input tosaid cavity above a predetermined value.

6QA gas4 discharge device for ultra high frequencies, comprising agas-filled cavity resonator resonant at the operating frequency of saiddevice, means coupled to said resonator for supplying ultra yhighfrequency energy to said cavity resonator, means coupled to saidresonator for abstracting energy from said resonator, and means operablyconnected to. said reso-nator for maintaining a cold discharge withinsaid resonator` at a' voltage anti-node thereof spaced from said energysupplying and abstracting means.

7. High frequency apparatus comprising an enclosed, gas-filled cavityresonator, means including a window in the wall of said resonator forcoupling high` frequency energy thereto at a voltage anti-node thereofand means including a second window in the wall of said resonator forcoupling high frequency energy therefrom, said resonator having a highermode of resonance at the operating frequency of said device, and said 13prising means forming .a quarter-wave transmission line section havingsaid joint as a termination, said section being connected at its outerend to a quarter-wave short-circuited transmission line section inseries with a leakage gap E whereby leakage of high frequency energythrough said gap is minimized.

9. A -high frequency system wherein a cylindrical high frequency deviceis removably coupled guides, comprising a hollow cylindrical holder bodysurrounding saidl device and having said rectangular guidescommunicating with'the interior thereof, a quarter-wave deep annulargroove extending radially in saidbody at a distance of a gquarter-wavelength above and belowsaid guide, whereby leakage ofhighfrequency energy axially of Vsaid device Vdue rto clearance betweensaid holder and saiddevice is minimized.

10. A'high frequency system, wherein a cylinto a pair of waveguides,comprising a hollow cylindrical holder body adapted to surround saiddevice and having said guides communicating with the interior thereof,said body having au.;

quarter-wave deep slot formed .therein extending parallel to one edge ofone.of .said .guides and spaced a quarter-wavelength therefrom, wherebyleakage of high frequency energy due to clearance between-said holderand saidtdevice is minimized.

1l. The combination as in `claim 10 wherein the depth of said slot isformed axially and wherein said slot extends annularly about said holderto prevent leakage axially of said holder `and device.

vice, a high frequency energy conductor xed to said holder andcommunicating with the interior thereof, and a high frequency deviceremovably and rotatably supported by said holder and comprising a casinghaving an opening therein for passage of high frequency energy, saidopening being normally opposite the end of said high frequency energyconductor communicating with said holder and being adapted to cooperatevaria,- bly therewith according to the rotary position of said device insaid holder.

i4. Apparatus comprising a high frequency device adapted to have highfrequency energy flow therethrough, a hollow holder removably supportingsaid device, said holder surrounding said device and having highfrequency energy conductors communicating with the interior thereof,said holder being spaced from said device, and means in said holder forpreventing leakage of high frequency energy between said conductors andaround said device.

l5. High frequency apparatus wherein an enclosed high frequency devicehaving apertures for the passage of high frequency energy is removablycoupled to high frequency conductors, comprising a holder for saiddevice including a hollow holder body surrounding said device and havinga pair of rotatable sections, each opposite one of said apertures, eachof said sections being fixed to one of said conductors to permit saidholder to be utilized with any one of a plurality of devices havingdiffering circumferential locations of said apertures.

to a pair of rectangular high lfrequency ywave :1,0

drical high frequency device is removably `coupled 16'. `The combinationas in claim 15 further including meansat the joint between saidconductors and said apertures for preventing leakage of fenergytherefrom.

` `1'7. High frequency apparatus comprising an enclosed, gas-filledcavity resonator having a cylindrical inner wall and two ends, and means4including a Iwindow in said cylindrical wall for coupling `highfrequency energy thereto, said .resonator having a higher mode ofresonance at Ithe operating frequency of 'saiddevica and said rwindowbeing located remote `from said ends of said resonator to facilitatefabrication thereof. `18. High frequency apparatus comprising a .highfrequency energy utilization device having .openings for the entranceand egress of high frequency energy,and a holder removably supportingsaid device `positioned adjacent to and Vspaced ffrom said device, saidholder support-- ing high frequency energy conductors opposite saidopenings and spaced therefrom by gaps, said holder including meanstherewithin for prevent- @ing leakage-of high frequency energy at saidgaps .betweensaid:conductors and said openings.

19. -High yfrequency apparatus comprising a .thigh :frequency energyutilization device having an opening for coupling high frequency energythereto, `a holder removably supporting said vde- .vice positionedadjacent to and spaced from said device, `and a high frequency energyconductor `fixedly supported by said holder opposite said ripening, saidholder including means therewithin lfor preventing leakage of highfrequency energy at the gap between said conductor and said iopening.

20. A high frequency system wherein a high frequency device is removablycoupled to a high frequency conductor, comprising means coupling saidconductor to said device, said coupling means comprising means removablyholding said device in a predetermined relation to said conductor toform an effective junction therebetween, and including means therewithinfor minimizing the impedance of the joint between said conductor andsaid device.

21. Apparatus as in claim 20, wherein said last named means comprisesmeans forming a quarter-wave transmission line section having saidjunction as a termination, said section being connected at its outer endto a quarter-wave shortcircuited transmission line section in serieswith the leakage gap between said device and said holding means, wherebyleakage of high frequency energy through said gap is minimized.

22. High frequency apparatus wherein an enclosed high frequency devicehaving apertures for the passage of high frequency energy is removablycoupled to a pair of high frequency conductors, comprising a holder forsaid device including a hollow holder body surrounding said device andhaving a pair cf sections each opposite one of said apertures, each ofsaid sections supporting one of said conductors, whereby high frequencyenergy may be led toward and away from said device.

23. High frequency apparatus wherein an enclosed cylindrical highfrequency device having axially displaced apertures in the cylindricalwall thereof for the passage of high frequency energy is removablycoupled to high frequency conductors, comprising a holder for saiddevice including a hollow holder body surrounding said device and havinga pair of sections each opposite one of said apertures, each of saidsections carrying one of said conductors.

24. High frequency apparatus comprising a high frequency energyutilization device having openings for the entrance and egress of highfrequency energy, and a holder for removably supporting said device andpositioned adjacent to and spaced from said device, said holdersupporting high frequency energy conductors opposite said openings andspaced therefrom by gaps and including means therewithin for preventingleakage of high frequency energy at said gaps between said conductorsand said openings, said leakage preventing means including resonanttransmission line means.

25. A high frequency system, wherein a cylindrical high frequency deviceis removably coupled to a pair of wave guides, comprising a hollowcylindrical holder body adapted to surround said device and having saidguides communicating with the interior thereof, said body having aquarter-wave deep slot formed therein, the depth of said slot beingformed radially of said body, said slot extending annularly of said bodyand parallel to one edge of one of said guides and spaced aquarter-wavelength therefrom, Where by leakage-of high frequency energyaxially of said holder due to clearance between said holder and saiddevice is minimized.

26. A high frequency system, wherein a cylindrical high frequency deviceis removably coupled to a pair of wave guides, comprising a hollowcylindrical holder body adapted to surround said device and having saidguides communicating with the interior thereof, said body having aquarter-wave deep slot formed therein, the depth of said slot beingformed radially of said 16 body, said slot extending axially of saidbody and parallel to one edge of one of said guides and spaced aquarter-wavelength therefrom, whereby leakage of high frequency energycircumf entially of said holder due to clearance betwe n said holder andsaid device is minimized.

27. Apparatus comprising a high frequency device adapted to have highfrequency energy ow therethrough, a hollow holder removably supportingsaid device, said holder surrounding said device and having highfrequency energy conductors communicating with the interior thereof,said holder being spaced from said device, and means in said holder forpreventing leakage of high frequency energy between said conductors and-around said device, said leakagepreventing means comprisingquarter-Wave sections of alternately wide and narrow clearance betweensaid device and said holder, whereby said energy is prevented fromflowing in the space between said device and said holder.

WILMER L. BARROW. WALTER W. MIEHER.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 2,106,770 Southworth et al. Feb.1, 1938 2,106,771 Southworth Feb. 1, 1938 2,128,234 Dallenbach Aug. 30,1938 2,153,728 Southworth Apr. 11, 1939 l2,300,052 Lindenblad Oct. 27,1942 Certificate of Correction Patent No. 2,454,761. November 80, 1948.

WILMER L. BARROW ET AL.

It is hereby certied that errors appear in the printed specification ofthe above numbered patent requiring correction as follows:

Column 11,line 56, claim 1, after means insert coupled to said secondelectrode; line 58, after the Word tube strike out the comma and insertinstead a period; same line beginning with whereby strike out all to andincluding the Word and period means in line 66 same claim; column 13,line 64, beginning with 15. High frequency strike out all to andincluding the Word and period therefrom. in line 4, column 14, andinsert instead the following:

15. High frequency apparatus comprising an enclosed, gas-filled cavityresonator having a cylindrical wall, and means in said wall for couplingthereto energy oj' a frequency required to form voltage antinodes at aplurality of positions therein, said coupling means being locatedadjacent one of said positions.

16'. Apparatus as in claim 15, wherein said resonator includes a pair ofopposed reentrant portions providing an internal gap near one end ofsaid resonator.

and that the said Letters Patent should be read With these correctionstherein that the same may conform to the record of the case in thePatent Office.

Signed and sealed this 5th day of July, A. D. 1949.

THOMAS F. MURPHY,

.Assistant Commissioner of Patents.

